Porting

[6.5 Detroit Diesel]

Just wondering, is there any value to getting the heads ported out more? Or would that be another waste of time and money?

[john8662]

No Dyno results pro or con.

But, I feel the most significant improvement from porting can be had on the exhaust side.

The intake side is pressurized on a turbo engine.

I guess it all depends on how much the porting job would cost.

[a5150nut]

No Dyno results pro or con.

But, I feel the most significant improvement from porting can be had on the exhaust side.

The intake side is pressurized on a turbo engine.

I guess it all depends on how much the porting job would cost.

If there is a turbo, wouldn't the exaust side be pressurized too?

[HammerWerf]

Detroit,

Find a post by RonnieJoe and read the articles he wrote about the work that went into his current engine in his Suburban.

As a follow-up, he has a post ( in this forum, I think) about some Turbo upgrade research he is doing. He is being coy, but the clues are tantilizing.

HammerWerf

[john8662]

2 main thoughts to material removal from head ports...

Gasket Matching

This where the gasket is the determining center of the ports. Positioning a gasket on the sealing surfaces and marking where material needs to be removed from the head and or matching manifold.

This helps to remove restrictions and obstructions that will chance the flow of air into the ports, and help remove turbulance spots.

Porting

This procecure is more involved and usually means removing material to shape the internal port in the chambers in the head (intake and exhaust) to increase flow through the heads themselves. This procedure helps be removing all rough casting formations within the ports as well as opening some spots up. This technique does require knowledge of air flow characteristics, because you can actually get wild with the cutting tool and do damage flow wise to the head and think you're doing good.


As for what's recommended?

Gasket Matching, open up the ports to the maximum the gasket requires, to not block flow into the heads and then out of the heads (creating hot spots).

Yes, the exhaust side would be pressurized via backpressure created by the turbo in the exhaust system.

Although I'm not sure what PSI pressure exists in this area under certain conditions.

J

[53internationalMiniBigRig]

ok here is my knowledge on porting, If you focus on porting only the exhaust side head port. first you must know the volumetric effecincy difference on the ports, say the intake flows 60cfm at .500 of lift at the valve and the exhaust flows 30cfm at .500 VL theres a 50% difference in flow, now if you bring up the VE what will happen is you will increase hp / torque at all RPM ranges without having to rev to a higher RPM, where as if you raise the CFM on the intake side the engine will make more power, but will do so at a higher RPM, and correct me if I am wrong but in a diesel is not the smartest thing to do. now on a gasket match, yes that is what most people do to improve engine breathing at all rpms but the same laws do apply so expect to see a slight powerband change. now keep in mind this is all stuff based on a gasoline engine, so some figures may change, but an engine is an engine so it should all be generally the same...